When Thanos turned up in the post-credits scene of The Avengers, it kicked into motion the Infinity storyline that will form the crux of Infinity War and the currently untitled Avengers 4.
Through multiple films since then, from Earth to Asgard and all around the Cosmos, we've been introduced to the powerful and mysterious gems known as Infinity Stones (actually called Infinity Gems in the comics), with Thanos himself intent on finding all of them to assemble the Infinity Gauntlet, which would give him all the power in the universe.
Through Guardians of the Galaxy Vol. 1 and Avengers: Age of Ultron in particular, the search for these Stones has been hotting up, but it's really going to kick off next year when Thanos finally heads to Earth and starts assembling the Stones on the Gauntlet.
The first trailer for Infinity War dropped yesterday, and among the many exciting reveals was the fact Thanos gets at least two of the Stones on his hand - but before we get to that movie, what's the state of play with them, and where (and what) are they?